Inmarsat 3-F1 was the first in a series of five third generation satellites. Launched from Cape Canaveral aboard an Atlas 2A rocket, it is currently in service over the Indian Ocean. It used the latest spot-beam technology and higher power to supply voice and data communications services worldwide to mobile terminals as small as pocket-size messaging units on ships, aricraft and vehicles.

INMARSAT-3 development was carried out by prime contractor Lockheed Martin and payload provider Matra Marconi Space. With an end-of-life power rating of 2,800 W, each INMARSAT-3 could deliver an IERP of up to 48dBW - eight times the INMARSAT-2 level - in L-band. It could dynamically reallocate both RF power and bandwidth among a global beam and five spot beams, allowing greater reuse of the available spectrums. Simultaneous voice channel capacity was up to eight times the INMARSAT-2 figure.

Each INMARSAT-3 also carried a navigation transponder designed to enhance the accuracy, availability and integrity of the GPS and Glonass satellite navigation systems.